Special report:

The military options

Take your pick

A tough set of choices

WHAT are the ways of fighting such a war? Michael O'Hanlon of the Brookings Institution offers four:

1. Kosovo-style air strikes against Afghanistan. This could be done by aircraft carriers in the Gulf (to where many extra combat aircraft have been sent) and/or stealth bombers flying from America. The combination of precision and heavyweight bombs could almost certainly destroy Mr bin Laden's camps and the Taliban's handful of military bases. But Mr bin Laden himself might well escape, along with much of his terrorism-planning staff. So might much of the Taliban's armoury—small arms, rocket-propelled grenades, 2,000-5,000 mortars and Stinger missiles that are deadly against helicopters.

2. Bombing other countries that help or shelter terrorists, not just Afghanistan. But the wider the attacks, the louder the protests in the Muslim world and elsewhere. The possible exception is Iraq. If Saddam Hussein were found to have been involved in last week's terrorism, attacks on his palaces and his Republican Guard might improve the chances of overthrowing him.

3. Invading Afghanistan. This would be the surest way of destroying the terrorists—if it worked. But it would require bases in either Pakistan or Iran, and preferably the help of their soldiers. Mr bin Laden might slip away. And, as both Britain and Russia can record, Afghanistan is no pushover. “Lice, dirt, blood,” is one Russian general's memory.

4. Commando raids plus support for the Afghan resistance. America has 5,000 Green Berets, 2,000 Rangers, 2,200 navy Seals and hundreds of men in the crack Delta Force. Britain has its own efficient special forces. Other countries might help. This is the likeliest way of killing or capturing Mr bin Laden. The anti-terrorism allies could also arm and train the anti-Taliban Northern Alliance, even though its leader, Ahmad Masoud, has just been killed. But Mr O'Hanlon reckons all this could take a long time, and cost hundreds of allied lives.